Digital video capabilities can be incorporated into a wide range of devices, including digital televisions, digital direct broadcast systems, wireless communication devices, personal digital assistants (PDAs), laptop computers, desktop computers, digital cameras, digital recording devices, video gaming devices, cellular or satellite radio telephones, and the like. Digital video devices typically implement a video compression technique, such as MPEG-2, MPEG-4, or H.264/MPEG-4, Part 10 (Advanced Video Coding (AVC)), in order to transmit and receive digital video signals more efficiently. Video compression techniques perform spatial and temporal prediction to reduce or remove redundancy inherent in video signals. Scalable video coding techniques enable additional features such as spatial, temporal and/or signal-to-noise ratio (SNR) scalability, via a base layer and one or more enhancement layers.
In video coding, video compression generally includes motion estimation and motion compensation. Motion estimation tracks the movement of video objects between successive video frames. Motion estimation generates motion vectors, which indicate the displacement of video blocks relative to corresponding video blocks in one or more reference frames. Motion compensation uses the motion vector to generate a prediction video block from one or more reference frames. In addition, motion compensation forms a residual video block by subtracting the prediction video block from the original video block. The video encoder applies transform, quantization and entropy coding processes to further reduce the bit rate of the residual block. A video decoder performs inverse operations to reconstruct the encoded video, using the motion vectors and residual information for each of the blocks.